Yieldable lineal seal



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Dec. 6, 1955 N. RANSOHOFF 2,725,643

YIELDABLE LINEAL SEAL Filed June 1, 1953 2 Sheets-Sheet l INVENTOR.

ATTORNEYS.

N. RANSOHOFF YIELDABLE LINEAL SEAL.

2 Sheets-Sheet 2 flTTOK/VEYS.

Dec. 6, 1955 Filed June 1, 1955 United States Patent I 2,725,643 YIELDABLE LlNEAL SEAL Nathan Rausohofh'Cihcinnati, Ohio, assignor to N. Ransoholf, Incorporated, Hamilton, Ghio, a corporation of Ohio Application June'1,'1953,'Serial No. s,.s17

8 Claims. 01. 34-242 escape of chemical liquids and fumes from the interior e of the tunnel.

A typical treatment tunnel for which the seal is utilized comprises a longitudinal tunnel housing having open charging and delivery ends for the passage through the tunnel of successive workpieces. Internally, the tunnel may include a series of transverse partitions which delineate treatment chambers, the partitions having openings through which the workpieces pass from chamber to chamber. The workpieces, such as fabricated metal parts, are advanced by means of an overhead conveyor parallel with the slot and extending above the top of the tunnel housing. From the overhead conveyor the work hangers depend downwardly through the slot with the workpieces suspended from the lower ends of the hangers to be advanced through the interior of the tunnel.

The present lineal seal is mounted along the opposite side edges of the slot and, as explained later, provides a closure which prevents the escape of chemical liquids and vapors which are maintained in a turbulent state within the tunnel. The chemical solutions are applied to the work by sets of spray pipes located in the respective chambers and arranged to direct jet streams of liquid chemical solutions at high velocity upon the workpieces as they pass through the chambers. By way of example, the solutions may be designed to cleanse the work surfaces of oils, greases and other surface film and to etch the surface preparatory to a plating operation. It Will be recognized that the jet streams will create chemical vapors and that the streams also will be deflected from the workpieces upwardly toward the slot.

Because of the corrosive nature of the solutions, the deflected streams and vapors would normally be deposited upon the overhead conveyor and upon the external surfaces of the tunnel housing, causing dissolution of conveyor lubricant and corrosive action leading to eventual failure of the metal conveyor parts and sheet metal housing. It will also be recognized that the vapors are dangerous to health and must be confined within the tunnel.

A primary object of the invention has been to provide a separable lineal seal coextensive with the longitudinal slot of a treatment tunnel or other exclosure and capable of preventing the escape of vapors and deflected streams of chemical solution, but sufliciently yieldable to separate. locally in response to the lineal advancement of the work supporting members without substantial leakage or resistance to the lineal advancement of the members along the seal.

Briefly, in its preferred form, the'yieldable seal comprises a pair ofdilatedparallel tubes or water bags ex- 2: tending along-opposite sides of the slot in contact with one another lineally, the tubes being formed of highly flexible sheet materiaL-such as rubber or the like. The tubes are dilated under relatively light pressure and their adjacent walls are in contact longitudinally under relaxed engagement, providing an interface having a substantial area in cross "section. The tubes are dilated preferably under hydrostaticpressure, being filled partially with water such that their adjacent inner sides are maintained lightly in balanced engagement to form the interface along the axis'of the slot.

By virtue of the'flexibility of the thin-walled tubes and the weight of the water confined within them, the two walls along the interface conform readily to the cross section of the hangers which extend through the interface. This allows the hangers to advancelongitudinally with very little impedance'and with substantially no leakage through'the interface. In other words, the interface separates immediately in advance of the leading side of the advancing'hanger andcloses at the trailing side, creating only a slight crevice along opposite sides of the hanger which, for all practical purposes, prevents the escape of vapors or liquid droplets.

According to-the preferred embodiment of the invention, the tubes are partially'filled with water to a common liquid level which dilates them to a generally tearshaped cross section. The slot is relativelywide and the sides of the respective tubes converge upwardly to a thin upper edge. These edges are joined along the opposite edges of the slot such that the lower portions of the tubes bulgeinwardly toward one another to form the interface. The-slot preferably includes vertical walls extending from its-side edges downwardly into the'tunnel and engaging the outer walls of the dilated tubes which also dependdownwa'rdly'into the tunnel. Thus thetubesare confined laterally between the walls to maintain theirposition; the walls also reacting against their internal pressure to provide the sealing interface.

A further object ofthe invention has been to'prevent wearin giof the'thin tube-walls along the sealing interface by utilizing replaceable wear strips which overlie the tubes and extend through the interface to provide bearing surface for the advancing-work hangers.

The wear strips: are formed of thin flexible sheet material similar to the tube walls and the'strips are attached at their upper edges along the slot adjacent the upper edges of the tubes. The strips depend in relaxed condition over the inner surfaces of the tubes and extend through the interface'with their lower edges hanging loosely below the lower edges of 'thetubes. The wear strips are attached independently of the tubes'such that they may be replaced without disturbing the tubes or deflating them.

Although the yieldable tubes may be of one-piece construction, extending for the full length of the slot, it is also contemplated to construct them in longitudinal sections with the sections disposed in endto end relationship -as indicatedin Figure 2. In this event, the wear strip may. be of related sectional construction, the sections being overlapped in the direction of hanger advancement' and extending across the adjoining ends of the tubes. The overlapped portions thus provide additional resistance across the interrupted ends of the tubes to form a con tinuousseal through the slot. e In orderto prevent interference between the hanger and the ends of the tubes and wear strips at the charging end of 'the slot,- thetunnel housing is provided with a pair of metal strips arranged to form a. converging throat leading into the sealing inter-face. The'converging throat overlies the ends of the tubes and-Wear strips for protection and guides .thehangers laterally into the interface for advancement through it.

According to the preferred construction, each tube or water bag is formed from an elongated sheet of thin pliable material overlapped upon itself to bring its opposite edges together. The edges are then doubled over and the joint thus formed is clamped along the slot to support the tube. Water supply fittings are in communication with the interior of the tubes from opposite sides. The fittings may be arranged to provide a common head pressure such that the two tubes develop equal or balanced pressure against opposite sides of the hanger at the interface.

Although the tubes are preferably dilated under hydrostatic pressure, it will be understood that under certain conditions it may be desirable to utilize air pressure to inflate them. In this case, the air pressure may be regulated to suit any particular operating requirement. It will be evident that in either event the tubes are effective to provide passage of the hangers and prevent the escape of vapors and liquid from the tunnel.

Other features and advantages of the invention will be more fully apparent to those skilled in the art from the following detailed description taken in conjunction with the drawings.

In the drawings:

Figure 1 is a side elevation of a chemical treatment tunnel embodying the present lineal seal, the tunnel being partially broken away to illustrate the relationship of the overhead conveyor, treatment chambers and other component parts.

Figure 2 is a general top plan of the treatment tunnel projected from Figure 1 and partially broken away to further illustrate the structure.

Figure 3 is an enlarged cross sectional view taken on line 33, Figure 1, illustrating the interior of the treatment tunnel and the relationship of the sealing tubes along the longitudinal slot of the tunnel.

Figure 4 is an enlarged fragmentary cross section taken on line 4-4, Figure 1, illustrating in detail the construc tion of the dilated sealing tubes, wear strip and mounting structure.

Figure 5 is an enlarged fragmentary side view of one of thte dilated tubes showing the end closure means of the tu e.

Figure 6 is an enlarged fragmentary bottom view of the dilated tube as projected from Figure 5.

It will be recognized that the present seal structure is adapted to a wide range of uses and that the present disclosure is selected to best illustrate its operating principles. According to the treatment tunnel disclosed in the drawings, metal workpieces are advanced continuously by an overhead conveyor through successive chambers in the tunnel where they are exposed to a sequence of jet spray treatments. The treatment sprays may consist of alternate chemical solutions and clear rinse water, each chemical treatment followed by a clear water rinse to prevent contamination by residual chemical solutions which adhere to the work surfaces. The liquid is projected upon the surface of the work by sets of spray pipes located in the successive chambers, each set of pipes directing high velocity jet streams from opposite sides of the chambers toward the work which is advanced along the center of the tunnel from chamber to chamber.

Although the chemical solutions are varied as dictated by the type of metal and other factors, the operating prin ciple is substantially the same in all installations. As a typical example, the treatments may be designed to remove from the work all traces of surface film, such as oils and greases, followed by an etching treatment to condition the surfaces for the deposit of a plating film. In preparing the work for plating, the tunnel may be arranged to apply an alkali treatment, a clear water rinse, an acid treatment, a second clear water rinse; thereafter this sequence may be repeated in combination with detergent treatments and finally an etching treatment followed by a clear water rinse.

The liquid solutions are supplied to the spray pipes preferably by individual circulatory systems, one for each chemical solution. Upon being projected upon the surface of the work, the liquid drains from the work surfaces and from the interior walls of the tunnel into a sump which is provided for each chamber in the lower portion of the tunnel. The solution which accumulates in the sumps is withdrawn by the circulatory systems and recirculated under pressure back to the spray pipes.

It will be understood that the chemical solutions draining into the individual sumps must be kept separate to avoid contamination; therefore the treatment chambers and sumps are arranged to prevent commingling of the droplets of liquid in adjacent chambers or leakage between adjacent sumps. As a further preventive against contamination, each chemical treatment is preferably followed by a clear water rinse bath as explained earlier. Since the circulating systems for the liquid solutions do not form a part of the present invention and are well known in the art, the pumps, piping and other related parts have been omitted from the drawings.

Referring to Figure 1 of the drawings, the treatment tunnel, which is indicated generally at 10, consists of an elongated horizontal housing fabricated from sheet metal and having openings at opposite ends to receive and discharge the advancing work pieces. The housing is generally rectangular in cross section, as shown in Figure 3, and includes a series of partitions 11 which extend transversely between the side walls 12-12 and across the longitudinal axis of the housing. The partitions are spaced apart longitudinally of the housing and thus divide the tunnel into a series of individual treatment chambers 13 disposed in end-to-end relationship. The central portion of each partition is configurated to provide an opening or internal profile 14 (Figure 3) which is common for all the partitions. The openings 14 of successive partitions are in alignment and collectively form a passageway extending for the length of the tunnel to allow the workpieces 15 to enter the tunnel and pass through the chambers without interference. It will be noted in Figure 1 that the end walls 16-16 of the tunnel are provided with similar openings constituting a charging opening 17 and a delivery opening 17a.

It will be observed in Figure 2 that each chamber 13 includes a series of spray pipes 13 which are disposed vertically at opposite sides of the chamber. The liquid solution and rinse water is projected continuously from opposite sides of the chamber such that the streams impinge upon all surfaces of the advancing workpieces. The liquid which drains from the workpieces and from the side walls of the housing flows by gravity to the bottom of the housing which forms a sump indicated generally at 20. It will be noted that each transverse partition includes a connecting section 21 extending across the bottom of the tunnelto form the end wall between the adjacent sumps.

As shown in Figure 1 an outlet pipe 22 is in communication with the respective sumps and forms a part of the liquid circulatory system. The liquid is supplied under pressure to the spray pipes by means of the horizontal manifolds 23 which are preferably arranged in pairs at opposite sides in the lower portion of the housing, one pair for each chamber. In the arrangement shown, the pairs of manifolds are connected in common by supply pipes 24 which extend crosswise of the housing and having their outer ends passing outwardly through the side walls of the housing. The supply pipes are connected to the circulatory systems of the several chemical solutions and rinse water supply according to the requirements of the various chambers.

According to the present arrangement, the spray pipes 18 are threaded directly into the manifolds at spaced points, as shown in Figure 1, and the manifolds may be mounted upon suitable brackets (not shown) to support them within the housing. Each spray pipe includes a series of apertures or nozzles which are adapted to project the jet streams of liquid toward the surfaces of the workpieces.

The housing, partitions and sump may be of welded or riveted construction, and the internal surfaces, which are exposed to the chemical solutions and fumes, are suitably coated' to prevent corrosion of the metal surfaces;

As explained above, the charging and delivery ends of the tunnel are provided with openings 17 and 17a which form passageways for the workpieces as they are transported through the tunnel by the overhead conveyor 25.

'In order to prevent the escape of corrosive chemical fumes outwardly through these openings, an air exhaust system, including suitable blowers, is connected by ducts 26 to the tunnel housing. It will be understood that the chemical fumes are injurious to health and have a corrosive action upon the surfaces of metal which may be exposed to the fumes. The exhaust system withdraws the free chemical fumes and maintains a constant flow of air inwardly through the charging and delivery openings. In other words, the exhaust system provides free passage of the workpieces but prevents the escape of chemical fumes from the open ends of the tunnel. The exhaust system is of conventional design well known in the art, and its structural details have been omitted from the drawings.

As explained earlier, the workpieces are suspended from the overhead conveyor 25 by work hangers 2'7 which extend downwardly through a longitudinal slot 28 into the tunnel. The slot is located at the longitudinal axis of the tunnel top 30, extending for its full length from the charging to the delivery end. The conveyor is of conventional design and usually forms a part of a production line. Thus the workpieces may be transported by the conveyor directly from the fabricating machines and through the tunnel for surface treatment. After passing through the tunnel, the work may be transported by the conveyor directly to the plating machines or other finishing equipment.

As best shown in Figure 3, the conveyor essentially comprises a rail 31 located above and parallel with the slot 28, and includes spaced trolleys 32 tracked upon the rail. The trolleys are advanced continuously by a conveyor cable or chain 33 which is connected in common to the trolleys and driven by the usual conveyor driving system. Each trolley includes a depending hanger 27 having its upper end pivotally connected to the trolley as at 34 and having a hook 35 or other means at its lower end suitable to engage the workpiece.

It will be understood at this point that the high velocity jet streams of chemical solution impinging upon the surfaces of the workpieces are deflected in all directions and that a certain percentage of liquid in the form of mist and liquid spray would normally escape upwardly through the slot 28 and would be deposited upon the top of the housing and upon the conveyor system. Because of the corrosive action of the chemical solution, theconveyor system and adjacent parts would be subjected to rapid deterioration and eventual destruction. In other words, the solution would not only wash away the lubricant but, after having done so, would attack the bearing surfaces and eventually cause failure of the entire system. Moreover, the slot would admit air into the tunnel and thereby allow the escape of chemical fumes in spite of the exhaust system, by reducing or destroying its effectiveness.

The yieldable seal, which is indicated. generally at 36, depends downwardly along the opposite sides of the slot and is effective to prevent the escape of acid fumes and deflected droplets of liquid solution. The seal therefore protects the conveyor mechanism and also renders the exhaust system effective by blocking the flow of air inwardly through the slot, thereby restricting the air flow to the charging and delivery openings. As explained later, the seal offers very little resistance to the longitudinal passage of the hangers transporting the workpieces through the tunnel since it is readily yieldable in response to the advancement of the hangers.

As best shown in Figure 4, the yieldable slot seal consists of a pair of thin walled, dilated tubes or water bags 3737 which are coextensive with the slot along its opposite sides. The upper edges of the tubes are secured along the edges of the slot with the tubes depending by gravity within the tunnel. As explained earlier, each bag is partially filled with water, causing its lower portion to bulge inwardly, such thatthe adjoining side portions of the bags relax lightly against one another under hydrostatic pressure to provide a sealing interface 38 extending axially along the center of the slot.

The sealing interface thus provided has a substantial vertical area as indicated at A, which extends longitudinally for the full length of the slot. This provides an efiicient closure against the escape of liquid and fumes and, by reason of the relaxed engagement of the bags against one another, reduces to a minimum the impedance upon the hangers as they advance through the interface. As best shown in Figure 3, the upper portion of the tunnel is provided with spaced walls 3939 which delineate the sides of the slot 28 and join the top wall 30 of the housing. These walls provide a rigid backing with the tubes resting against the walls and bulged inwardly toward one another.

The tubes are formed from strips of relatively thin flexible material such as rubber, synthetic rubber or plastic material. The tubes are created by overlapping the sheet upon itself and doubling the edges over to provide a crimped joint as indicated at 49. The crimped edges are then clamped to seal the tube and to support it in operating position.

According to the preferred structure as shown in Figure 4, each tube is mounted by means of an angle iron 41 mounted along the upper edge of the slot on opposite sides. The crimped upper edge of the tube is interposed between the angle iron and the wall 39 and the two members are drawn into clamping engagement by a series of screws 42. As detailed in Figure 5 the opposite ends of the tube are sealed off by means of clamping strips 43 clamped against the opposite sides of the bag by means of the screws 44.

The thin side walls of the tubes in the sealing area are protected against wear due to the friction of the advancing hangers by the wear strips 4545 which overhang the inner surfaces of the tubes. The wear strips depend below the meeting areas of the tubes and their lower portions rest lightly against one another at the sealing interface and bear against the hangers as they pass through the slot. The wear strips are fabricated from relatively thin flexible material similar to the tubes and their upper edges are attached along opposite edges of the slot above the tubes. In order to provide for convenient replacement of the strips upon being worn, they are arranged to be removed and replaced without disturbing the tubes.

For this purpose, the upper edge of each wear strip is clamped upon the angle iron 41 by a. second angle iron 46, which is clamped upon the wear strip by a series of screws 47. The screws preferably are threaded into the lower angle iron 41 and allow the angle iron 46 and wear strip 45 to be removed without disturbing the mounting of the tube.

Although the tubes may be sufficiently long to-extend without interruption for the full length of the tunnel, in the alternative, they may be arranged in sections which reside in end to end alignment with one another. The sectional construction may be utilized for exceptionally long treatment tunnels; thus if one portion of the seal becomes worn, it can be replaced individually at minimum cost and labor. For the same reason, the wear strips may be of sectional construction with their adjoining end over- 7 lapped as at 48, in the direction of conveyor travel as indicated in Figure 2.

In the arrangement shown, the wear strips are somewhat longer than the tubes, with the overlapped portions 48 extending across the adjacent ends of the tubes. This arrangement provides a double thickness of material bridging and sealing the area between adjoining ends of of the tubes. It will be understood that upon being worn, one or more of the wear strip sections may be replaced without disturbing the tubes or the wear strip sections which are in serviceable condition.

As shown in Figure 2, the charging end of the slot is provided with a pair of metal protector plates 5050 arranged to prevent interference by the conveyor hangers with the ends of the tubes as the hangers enter the slot at the charging end. The protector plates each include a curved portion 51 which is preferably welded as at 52 to the end wall of the housing adjacent the open end of the slot. The curved portion of each protector extends in an are spaced outwardly from the end of the tube and each includes a straight extension or tail-piece 52 which overlies the wear strip and tube. It will be noted that the curved portion of the protectors in assembly form a throat indicated at 54 which converges toward a slot 55 which is delineated by the spaced tail-pieces.

As the hangers approach the charging end of the tunnel their shank portions enter the converging throat, such that the throat guides them into the restricted pasageway to the sealing interface. The hangers may be formed either of round or flat stock and the passageway is sufiiciently wide to admit the hangers freely. After passing beyond the rearward ends of the tail-pieces, the hangers are engaged by the interface for advancement through it of liquid, each tube is provided with an L-shaped pipe fitting 56 which passes through the rear wall of the tube and through the sheet metal wall as shown in Figure 4. The lower end of the L-shaped pipe fittings is clamped in sealing engagement with the tube by means of clamp collars 5757 engaging the opposite sides of the tube wall. The fitting may be clamped to the sheet metal wall 39 by a collar 58 to provide mechanical support.

The vertical limb of the pipe fitting is in communication with a trough 60 which is common to all of the tubes of the series. Water is supplied to the trough by means of a supply line 61 which extends from one of the fresh water spray pipes 18 at opposite sides of the tunnel. The supply line may be arranged to provide a constant trickle of water during operation of the apparatus so as to replenish the water supply at all times in an automatic manner. Alternately, valves may be inserted in the supply lines to allow filling and replenishment of the bags periodically.

From the foregoing description, it will be recognized that the dilated tubes provide a relaxed lineal pressure seal which provides a uniform sealing action for the full length of the slot. If hydrostatic pressure is utilized to dilate a series of sectional tubes as described, a head pressure is provided by the trough 60 which is common to all the bags of the series. If the two tubes are continuous, then the head pressure is constant for the full length of the two tubes, assuming them to be mounted in a level plane. It will also be recognized that the same result obtains if the tubes, whether continuous or sectional, are inflated by air or gas pressure from a source which is common to all the tubes.

It is to be noted that the dilated bags depend downwardly within the slot due to the weight load of the liquid confined within them. This allows the tubes to be mounted in a simple manner along their upper edges as disclosed, taking advantage of the tear-drop cross section to provide the sealing interface. Although it is preferable to control the pressure of the interface by utilizing the spaced backing walls 39, it is also contemplated to In order to fill the tubes and compensate for any loss omit the walls, allowing the tubes to rest in balanced condition against one another by gravity due to their cross sections and respective centers of gravity.

It will also be observed that the wear strips are utilized only to preserve the thin-walled tubes against wear; there fore the Wear strips may be omitted if the operating conditions are less rugged and if the tubes are extended for the full length of the slot.

Having described my invention 1 claim:

1. In a treatment tunnel for treating workpieces, a housing having a passageway extending lineally therethrough, a conveyor mounted above the housing and extending parallel with said passageway, work hangers depending from said conveyor and extending downwardly through said passageway into the interior of the tunnel, the work hangers adapted to suspend the workpieces upon their lower ends and advance the pieces through the interior of the housing, a pair of dilated tubes suspended along opposite sides of said passage and sealed in relation to the housing, said tubes depending downwardly into the housing, a pair of opposed vertical side walls spaced apart from one another and depending downwardly into the housing along opposite sides of the slot, said dilated tubes being confined between said walls, said tubes contacting one another and providing a sealing interface extending lineally along the passageway, the interface yielding locally along the leading side of the advancing work hangers and closing along the trailing side, thereby providing a substantially continuous seal for said passageway during the advancement of the work hangers therethrough.

2. In a treatment tunnel for treating workpieces, a housing having a passageway extending lineally therethrough, a conveyor mounted above the housing and extending parallel with said passageway, work hangers depending from said conveyor and extending downwardly through said passageway into the interior of the tunnel, the work hangers adapted to suspend the workpieces upon their lower ends and advance the pieces through the interior of the housing, a pair of relatively thin-walled, yieldable tubes suspended along opposite sides of said passageway, said tubes being at least partially filled with liquid and thereby dilated under hydrostatic pressure, the respective tubes being sealed in relation to the housing and depending downwardly, a pair of opposed vertical side walls spaced apart from one another and depending downwardly into the housing along opposite sides of the slot, said dilated tubes being confined between said walls the adjoining side walls of the tubes being in contact with one another providing a sealing interface extending lineally along the passageway, the thin walls which form the interface being yieldable locally along the leading side of the advancing work hangers and closing along the trailing side, thereby providing a substantially continuous seal for said passageway during the advancement of the work hangers therethrough.

3. In a treatment tunnel for workpieces, a housing having a slot extending lineally therethrough, work hangers extending from points outside the housing through said slot, means outside the housing for advancing work hangers lineally along the slot, a pair of sealing tubes formed of pliable sheet material and extending parallel with one another along the slot, said tubes being sealed relative to the housing and being attached to the housing along opposite sides of the slot, said tubes being at least partially filled with liquid and thereby dilated under hydrostatic pressure, the respective tubes depending downwardly by gravity into the housing and bulged inwardly toward one another, a pair of opposed vertical side walls spaced apart and depending downwardly into the housing along the opposite sides of the slot, the dilated tubes being confined between the spaced side walls and in contact with one another under hydrostatic pressure, and a pair of wear strips formed of pliable sheet material, said strips being attached along opposite sides of the slot and depending downwardly over the dilated tubes, the lower portions of said strips being engaged between the tubes and providing a sealing interface which is yieldable locally-in response to the advancing work hangers, thereby providing a substantially continuous seal for said slot.

4. In a treatment tunnel forworkpieces, "a housing having a slot extending lineally along a wall thereof, work hangers adapted to traverse said slot, the slot having a charging end receiving the said hangers for advancement therethrough, a pair of sealing tubes formed of pliable sheet material and extending parallel with one another along the slot, said tubes being sealed relative to the housing and being attached to the housing along opposite sides of the slot, said tubes being at least partially filled with liquid and thereby dilated under hydrostatic pressure, the respective tubes depending downwardly by gravity into the housing and bulged inwardly toward one another, a pair of opposed vertical side walls spaced apart and depending downwardly into the housing along the opposite sides of the slot, the dilated tubes being confined between the side walls in contact with one another under hydrostatic pressure to provide a sealing interface which is yieldable locally in response to the advancing work hangers, said sealing tubes having ends terminating at the charging end of the slot, and a pair of protector members overlying the respective ends of the tubes at the charging end of the slot, said protector members providing a converging throat leading into the sealing interface and adapted to guide the advancing work hangers at the charging end into the interface.

5. A yieldable seal for a lineal slot extending along the wall of a treatment tunnel or the like, said seal adapted normally to seal off the slot and to yield locally in response to the advancement of work hangers which extend from points outside the tunnel through the slot into the tunnel, said yieldable seal comprising a plurality of sectional seal ing tubes formed of pliable sheet material, said tubes being mounted in alignment with one another along opposite sides of said slot with the ends of the tubes adjacent one another, said tubes being dilated by internal fluid pressure and being sealed relative to the tunnel along opposite sides of the slot, a series of sectional wear strips, said wear strips being substantially longer than the sectional sealing tubes, said sectional wear strips each having an edge attached to the tunnel at opposite sides of the slot, said strips overhanging the adjacent sides of the tubes and depending downwardly therebetween, the opposite end portions of the respective strips extending beyond the adjacent ends of the sectional sealing tubes with the endwise portions of adjoining strips overlapped one upon another in the direction of the advancement of the work hangers, said dilated tubes bulging toward one another with the wear strips in contact with one another to provide a sealing interface, the overlapped portions of the wear strips extending across the adjoining ends of the tube sections to provide a sealing interface spanning the ends of the tubes, said interface yielding in response to the advancement of the work hangers, whereby the interface provides a substantially continuous seal with respect to the advancing work hangers.

6. A yieldable seal for a lineal slot extending along the wall of a treatment tunnel or the like, said seal adapted normally to seal off the slot and to yield locally in response to the advancement of work hangers which extend from points outside the tunnel through the slot into the tunnel, said yieldable seal comprising a plurality of sectional sealing tubes formed of pliable sheet material, said tubes being mounted in alignment with one another along opposite sides of said slot with the ends of the tubes adjacent one another, respective liquid supply means in communication with the respective sectional tubes along opposite sides of the slot, said liquid supply means supplying liquid to the tubes in common to a liquid level thereby dilating the tubes under equal hydrostatic pressure, a series of sectional wear strips, said wear strips being substantially longer than the sectionalsealing tubes, said sectional wear strips each having an edge attached to the tunnel at opposite sides of the slot, said strips overhanging the adjacent inner sides of thestubes and depending downwardly therebetween, the opposite end portions of the respective strips extending beyond the adjacent ends of the sectional sealing tubes with the endwise portions of adjoining strips overlapped one upon another in the direction of the advancement of the work hangers, said dilated tubes bulging toward one another with the wear strips in contact with one another to provide a sealing interface between the tubes, the overlapped portions of the wear strips extending across the adjoining ends of the tube sections to provide a sealing interface spanning the ends of the tubes, said interface yielding in response to the advancement of the work hangers, whereby the interface provides a substantially continuous seal with respect to the advancing work hangers.

7. A yieldable seal for a lineal slot extending along the wall of a treatment tunnel or the like, said seal adapted normally to seal off the slot and to yield locally in response to the advancement of work hangers which extend from points outside the tunnel through the slot into the tunnel, said yieldable seal comprising a plurality of sectional sealing tubes formed of pliable sheet material, said tubes being mounted in alignment with one another along opposite sides of said slot with the ends of the tubes adjacent one another, a pair of liquid supply troughs in communication with the respective sectional tubes along opposite sides of the slot, means in communication with said liquid supply troughs adapted to supply liquid to the troughs, said troughs adapted at least partially to fill all of said sectional tubes to a common liquid level thereby dilating the tubes under equal hydrostatic presssure, a series of sectional wear strips, said wear strips, being substantially longer than the sectional sealing tubes, said sectional wear strips each having an edge attached to the tunnel at opposite sides of the slot, said strips overhanging the adjacent interior sides of the tubes and depending downwardly therebetween, the opposite ends of the respective strips extending beyond the adjacent ends of the sectional sealing tubes with the endwise portions of ad oining strips overlapped one upon another in the direction of the advancement of the work hangers, said dilated tubes bulging toward one another with the wear strips in contact with one another to provide a sealing interface between the tubes, the overlapped portions of the wear strips extending across the adjoining ends of the tube sections to provlde a sealing interface spanning the ends of the tubes, said interface yielding in response to the advancement of the work hangers, whereby the interface provides a substantially continuous seal with respect to the advancing work g l k yieldable seal for a longitudinal slot extending through the wall of an enclosure, said seal adapted'to normally seal off said slot and to yield locally in response to the advancement along the slot of work conveying members which extend through slot, said seal comprising, a pair of tubes, each of said tubes formed ofa sheet o f relatively thin pliable material, saidsheet being doubled upon itself lengthwise and having its longitudinal edge portions clamped together to form a tube, the clarrlipe edges of said tubes be1ng secured in parallelism a ong opposite sides of the slot, said tubes being at least partially filled with liquid and dilated to a generallytear-shaped configuration in cross-section, the tubes having their respective side walls in conta ct with one another to provide a sealing interface longitudinally coextensive with the slot, the thin pliable walls which constitute the sealing interface being yieldable locally along the leading sides of the advancing work conveying members and closing along the trailing side, whereby the tubes provide a substantially w 1'1 coextensive hydrostatic pressure seal extending longi- 2,073,669 tudinally of the slot. 2,239,714 2,344,475 References Cited in the file of this patent 2,5 4,599 UNITED STATES PATENTS 6 2,579,575

1,632,760 Jones June 14, 1927 12 V Zademach Mar. 16, 1937 Hammell -2 Apr. 29, 1941 Tm'nbull Mar. 14, 1944 Hapman Aug. 14, 1951 Herdlein Dec. 25, 1951 

